Selecting seed trees for a forest restoration program: A case study using Spondias axillaris

Background

Framework tree species are indigenous forest tree species, planted to complement and accelerate natural regeneration of forest ecosystems and encourage biodiversity recovery, on degraded sites. Spondias axillaris Roxb. (Anacardiaceae) is an exceptionally effective framework tree species for restoring seasonal tropical forest ecosystems to degraded sites throughout south and southeast Asia. This study identifies criteria for selection superior parent seed trees, based on nursery performance and field establishment, using Spondias axillaris as a case study.

Research goals & methods

Seed progenies were collected from 41 S. axillaris parent trees growing in Doi Suthep-Pui National Park in northern Thailand. Seeds were planted in nursery and field conditions and monitored over one year. Seedlings that survived in the nursery were more likely to have originated from small pyrenes, which germinated rapidly. Seedlings that survived in the field, over the first growing season, tended to be larger at time of planting than those that died.

Conclusions & takeaways

Twelve of the 41 seed trees met these standards and qualified as superior seed trees for forest restoration. Four standards for selection of superior seed trees for this species were recognised: 70%, or higher, seedling survival in the field; a sapling height of 100 cm or taller after the first growing season in the field; 40% or greater germination in the nursery; and 70% or higher seedling survival in the nursery. These criteria should be considered with expected growth rates for other species.